The polymerization of vinyl type monomers that contain pendant carboxylic acid functionality has always presented some unique challenges. For example, U.S. Pat. No. 5,223,592 reports that the critical aspect is to provide complete neutralization of an itaconic acid type monomer prior to conducting the polymerization reaction, where complete neutralization is identified as having two moles of base neutralizer for each mole of itaconic acid. U.S. Pat. No. 5,336,744 reports that polymers of itaconic acid are formed at high conversion by an aqueous polymerization process of partially neutralized monomer solution, water, polyvalent metal ion, and initiator.
Attention is also directed to U.S. Publication No. 2009/0286847 entitled “Polycarboxylic Acid Polymers” which relates to methods and polymer based upon vinyl type monomers that contain pendant carboxylic acid groups and ester group functionality.